Today's domesticated dogs are descended from wolves, and most retain predatory instincts. Small animals, such as rabbits, trigger your dog's prey instinct when they startle and flee from your dog. If your dog is able to catch the rabbit, he will usually take it and tear into it, eating some or all of his catch.
What's In It For Him
Although dogs' external appearances have changed due to selective breeding, their digestive systems remain similar to their wolf ancestors. The combination of raw meat, stomach contents and bones provide a tasty treat that appeals to your dog's primal instincts. While healthy dogs will not be adversely affected by bacteria in the rabbit's digestive tract or ingesting some of its hair, rabbits can carry rabies and you should make sure your dog's vaccinations are up to date.